FTDI Serial TTL-232 USB Cable
Just about all electronics use TTL serial for debugging, bootloading, programming, serial output, etc. But it's rare for a computer to have a serial port anymore. This is a USB to TTL serial cable, with a FTDI FT232RL usb/serial chip embedded in the head. It has a 6-pin socket at the end with 5V power and ground, as well as RX, TX, RTS and CTS at 3V logic levels. These are perfect for use with a Boarduino, Meggy's, or other Arduino clones and derivatives, and Fuzeboxen. Useful whenever you want to communicate with a TTL serial device, such as an XBEE.